1. Field of Disclosure
Three-dimensional (3D) imaging by Smart Pseudoscopic-to-Orthoscopic Conversion (SPOC) is disclosed that creates new sets of synthetic elemental images (SEIs) that are fully adapted to Integral Imaging (InI) display monitors, and allows full control of microlens array (MLA) display parameters.
2. Description of Related Art
Stereoscopic and auto-stereoscopic monitors usually produce visual fatigue to an observer due to the convergence-accommodation conflict (i.e., the discrepancy between actual focal distance and depth perception). An attractive alternative to these technologies is Integral Imaging (InI), which is a three-dimensional (3D) imaging technique that provides auto-stereoscopic images that can be observed without special glasses or goggles worn by the observer.
The InI concept is that one can create a 3D image of an object by acquiring many two-dimensional (2D) elemental images of it from different positions, which can be readily achieved by using a microlens array (MLA) as the camera lens. When the elemental images are projected onto a 2D display placed in front of an MLA, the different perspectives are integrated as a 3D image. Every pixel of the display generates a conical ray bundle when it passes through the array. The intersection of many ray bundles produces a local concentration of light density that permits object reconstruction. The resulting scene is perceived as 3D by the observer, whatever his or her position relative to the MLA. And since the InI monitor truly reconstructs the 3D scene, the observation is produced without special glasses or goggles, with full parallax, and with no visual fatigue.
A problem encountered with InI for 3D displays is the pseudoscopic (or depth reversed) nature of the displayed images when the captured elemental images do not receive pixel pre-processing. Okano et al. proposed a digital method to display orthoscopic scenes (Okano, “Real time pickup method for a three-dimensional based on integral photography,” Appl. Opt. (1997), vol. 36(7), pp. 1598-1603). While simple and efficient, Okano's method has the disadvantage that it provides only virtual reconstructions; i.e., the 3D scene appears inside the monitor.
More recently, a method was reported for creation of a set of synthetic elemental images (SEIs) that permit orthoscopic, real (or floating outside of monitor) reconstruction of the 3D scene by a digital technique, Smart Pixel Mapping (SPIM) (M. Martinez-Corral et al., “Formation of real, orthoscopic integral images by smart pixel mapping,” Opt. Express (2005), vol. 13(23), pp. 9175-9180). SPIM provided real, non-distorted, orthoscopic integral images by direct pickup. By proper mapping of pixels, SPIM allowed the creation of a set of SEIs which, when placed in front of an MLA that is identical to the one used in the capture, produces the reconstruction of a real and orthoscopic image at the same position, and with the same size, as the original 3D object. However, SPIM was limited by the fact that the method allows only a fixed position for the reconstructed scene, and also that the number of microlenses (and their pitch) cannot be changed.